There is a flaw that ruins the global enjoyment of the game, the explosion is to long. Also, the walls that you must explode are not using the level. They just feel like walls that slow you down, kinda like a loading screen, you must wait patiently while doing nothing more. Or else, if you really are speedrunning, you hold the button before arriving at that part. But the dashings are to strict, if you hold the button down, you can only go to a precise distance, there are parts that you can't get to while always holding. But if you release the button the explosion gets reset. A simple solution would be to make the explosion bar go down when you release shift instead of going straight to zero. It would also go well with the theme by cooling down when not holding.
Another problem I see is that (at least for me) there are 2 to 3 seconds of waiting at the start of each game. Maybe the game is instanciating everything and destroying everything each time. If it is the case, I would recommand not loading everything in the beginning and just deactivate what you explode, like pooling.
When ignoring the flaws stated previously, the game was really fun, quite hard to get the hold of but when you get it the game is good. I really like the particle effects of the fire and the speed of the dash when you get to speed up with it.